This invention generally relates to cargo containers; and more specifically, to cargo containers of the type from which bulk cargo is discharged by pulling a bottom or floor liner out from the container.
Standardized containers or boxes have come into very extensive use for the shipment of freight by land and sea, and the many advantages of such intermodal containers have made it very desirable to adapt them for use with as many types of cargo as possible. Accordingly, there have been attempts, with varying degrees of success, to use such standardized containers to carry bulk cargo such as dry bulk chemicals, powdered and pelletized resins, flour, coffee beans, and grains. In particular, considerable attention has been given over the last several years to transporting such cargo in bulk in standardized intermodal cargo containers--that is, in containers in which the cargo is loaded directly into the intermodal containers, without first being loaded or packed into smaller boxes or packages that are then loaded into the intermodal containers.
Commonly, when a cargo is transported in bulk in a large, intermodal container, the cargo is discharged from the container by tilting the container so that the cargo slides out the back of the container under the force of gravity. This type of discharging procedure is generally disclosed, for example, in U.S. Pat. Nos. 3,696,952 and 3,868,042 and in U.S. patent application Ser. No. 07/481,989, now U.S. Pat. No. 5,040,693. While this cargo discharging method has received significant commercial acceptance, it has a disadvantage in that it requires an expensive apparatus to tilt the container.
With another method for discharging bulk cargo from a cargo container, a pleated liner is first placed on the container floor when the container is empty, and then the cargo is loaded into the container, over the liner. To discharge the cargo from the container, the liner is pulled out from the cargo container, pulling the product out from the container with the liner. Canadian Patent 1,205,106 and U.S. Pat. Nos. 4,470,749 and 4,556,349 disclose this type of technique for discharging cargo. This cargo discharging procedure has not received widespread commercial use, however. A primary reason for the lack of commercial use is that, heretofore, the industry has not been able to provide a discharging method of this general type that, on the one hand, effectively unloads the entire contents of the cargo container, and on the other hand, is still comparatively simple and economically acceptable.